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Science Prof Online
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From the Virtual Cell Biology Classroom on ScienceProfOnline.com Image: Compound microscope objectives, T. Port
Tami Port, MS
Creator of Science Prof Online
Chief Executive Nerd
Science Prof Online
Online Education Resources, LLC
info@scienceprofonline.com
3. Genetics Terminology: Chromosomes & Genes
• ________ -
Complete complement
of an organism’s DNA.
• Cellular DNA is
organized in
___________.
• ______ have specific
places on chromosomes.
Image: Chromosome & gene, Graham Colm,
National Human Genome Research Institute From the Virtual Cell Biology Classroom on ScienceProfOnline.com
4. So who was Mendel?
• Once upon a time (1860's), in an Austrian monastery,
there lived a monk named Gregor Mendel.
• Mendel spent his spare time breeding pea plants.
• He did this over & over & over again, and noticed patterns
to the inheritance of traits, from one set of pea plants to
the next.
• By carefully analyzing his pea plant numbers, he
discovered three laws of inheritance.
• Mendel's Laws are as follows:
1. Law of Dominance
2. Law of Segregation
3. Law of Independent Assortment
• In his work, the words "chromosomes" or "genes" are nowhere to
be found. The role of these things in relation to inheritance &
heredity had not been discovered yet.
• What makes Mendel's contributions so impressive is that he
described the basic patterns of inheritance before the
mechanism for inheritance (namely genes) was even discovered!
The dude
was a
total
GENIUS!
Image: Gregor Mendel, Mendel's Principles of Heredity: A Defense
by Bateson, William; Spicoli from Fast Times at Ridgemont High From the Virtual Cell Biology Classroom on ScienceProfOnline.com
5. First, a little more genetics terminology.
Then…
Mendel's Laws
1. Law of Dominance
2. Law of Segregation
3. Law of Independent Assortment
Image: Gregor Mendel, Mendel's Principles
of Heredity: A Defense by Bateson, William. From the Virtual Cell Biology Classroom on ScienceProfOnline.com
6. Genetics Terminology
• __________: the genes of an
organism (all your genes)
• __________: an organism’s
traits (expression of your genes)
• ________: variations of a gene
• Represented with letters for
the different types of alleles
(PP, Pp, pp)
• __________: pair of identical
alleles for a character (PP, pp)
• __________: two different
alleles for a gene (Pp)
From the Virtual Cell Biology Classroom on ScienceProfOnline.com
7. Genetics Terminology
• Character: heritable feature (i.e.,
fur color)
• Trait: variant for a character (i.e.
brown)
• True-bred: all offspring of same
variety
• Hybridization: crossing of 2
different true-breds
We label the different
generations of a cross as:
• P generation (parents)
• F1 generation (1st filial generation)
• F2 generation (2nd filial generation)
From the Virtual Cell Biology Classroom on ScienceProfOnline.com
8. ___ ___
Dominant & Recessive
Genotypes & Phenotypes
____________ genotype:
Both recessive alleles must be present (rr).
___________ genotype:
At least one dominant allele is present (R-).
Character: Tongue Rolling
Being able to roll your tongue is a dominant
phenotype.
Harry: Being able to roll your tongue is the dominant trait
(phenotype). Q: How would we represent the genotype of he
was homozygous dominant?
Hermione: Not being able to roll your tongue is the
recessive (phenotype). Q: What would be the recessive
genotype?
___ ___
___ ___
Q: Would “Harriet” be able to roll her tongue?
Genetics Terminology
From the Virtual Cell Biology Classroom on ScienceProfOnline.com
9. • In a cross of parents that
are pure for contrasting
traits, only one form of the
trait will appear in the next
generation.
• Offspring that are hybrid
for a trait will have only the
dominant trait in the
phenotype.
Q: On last slide: If Harry’s was
heterozygous, what are the
possible genotypes for Harriet?
1. Mendel’s Law of _________
Image: Simple Inheritance, complete
dominance, Magnus Manske From the Virtual Cell Biology Classroom on ScienceProfOnline.com
10. 2. Mendel’s Law of ________
Image: Independent assortment and
segregation diagram, Mariana Ruiz.
Table showing how
the genes exchange
according to
segregation or
independent
assortment during
meiosis and how this
translates into
Mendel's laws.
• Alternative versions of
genes (alleles) result in
variations in inherited
characteristics.
• For each character, an
organism inherits 2 alleles
(one from each parent).
• The alleles for each
character segregate
(separate) during gamete
production (_______).
• Alleles for a trait are
recombined at fertilization,
becoming genotype for the
traits of the offspring.
From the Virtual Cell Biology Classroom on ScienceProfOnline.com
11. 3. Mendel’s Law of _____ ______
Image: Independent assortment and
segregation diagram, Mariana Ruiz.
Diagram of how the
genes exchange
according to
segregation or
independent
assortment during
meiosis and how this
translates into
Mendel's laws.
Alleles for different
traits are distributed
to sex cells (& offspring)
independently of one
another.
HELP! Show me a video!
Remember…Mendel came up with
this stuff BEFORE we know
about the existence of DNA,
genes, chromosomes.
WOW!
From the Virtual Cell Biology Classroom on ScienceProfOnline.com
12. 1. Law of Dominance:
- In a cross of parents that are pure for
contrasting traits, only one form of the
trait will appear in the next generation.
- Offspring that are hybrid for a trait will
have only the dominant trait in the phenotype.
2. Law of Segregations:
- During the formation of gametes (eggs or sperm), the two alleles
(hereditary units) responsible for a trait separate from each other.
- Alleles for a trait are then "recombined" at fertilization, producing the
genotype for the traits of the offspring.
3. Law of Independent Assortment:
- Alleles for different traits are distributed to sex cells (& offspring)
independently of one another.
Mendel’s Laws:
Image: Gregor Mendel, Mendel's Principles of
Heredity: A Defense by Bateson, William
From the Virtual Cell Biology Classroom on ScienceProfOnline.com
13. Figuring Out Patterns of Inheritance
A Punnett square is a tool for
diagramming the possible
genotypes of offspring.
Let do a Punnett square for the trait
of bent little finger (dominant
genotype), using letter “B” to
represent alleles:
• DAVID (the BabyDaddy):
- dominant phenotype [bent finger]
- Q: What is David’s gentoype?
• ME (the BabyMama):
- Recessive phenotype [straight finger]
- Q: What is my genotype?
LEO (the BabyBaby):
- Dominant phenotype [bent finger]
- Q: What is Leo’s genotype?
Image: Bent Little Finger” (B - ), David & Leo Port
David’s Genotype:
Tami’s
Genotype:
From the Virtual Cell Biology Classroom on ScienceProfOnline.com
14. So far, we’ve
discussed Simple
Inheritance &
Punnett Squares…
But, of course,
genetic is much
more complicated
than that.
Let’s explore:
• Incomplete dominance
• Multiple alleles
• Co-dominance
Image: Eye color, a polygenic phenotypic
character, Pennsylvania State University From the Virtual Cell Biology Classroom on ScienceProfOnline.com
15. Beyond Simple Inheritance: ________ ________
• Patterns of dominance
often go beyond simple
dominant or recessive
traits.
• Incomplete dominance
has “degrees”. It is not
complete.
F1 generation’s
appearance between the
phenotypes of the 2
parents.
Ex: snapdragons
The color alleles of Mirabilis jalapa are not dominant or recessive.
(1) Parental generation. (2) F1 generation. (3) F2 generation. The
"red" and "white" allele together make a "pink" phenotype, resulting in
a 1:2:1 ratio of red:pink:white in the F2 generation.
Image: Incomplete Dominance, Wiki Magnus Manske From the Virtual Cell Biology Classroom on ScienceProfOnline.com
16. Beyond Simple Inheritance: _________ ______
When there are more
than two possible
alleles for a gene.
Examples:
- eye color
- human blood types (ABO)
Image: Eye color, a polygenic phenotypic
character, Pennsylvania State University From the Virtual Cell Biology Classroom on ScienceProfOnline.com
17. Beyond Simple Inheritance: __________
Two alleles affect the phenotype in
separate, distinguishable ways.
Example: AB Blood Type
- has three alleles: A, B & O
- AB co-dominant, O recessive
- genotype represented using IA, IB & i
Phenotype Genotype
Type A IAIA or IAi
Type B IBIB or IBi
Type AB IAIB
Type O ii
Image: Bleeding wound, by Crystal From the Virtual Cell Biology Classroom on ScienceProfOnline.com
18. A little bit of immunology to help you understand blood types.
Immunology Terms
_______________
• Molecules that trigger a specific
immune response.
• Include components of bacterial cell
walls, plus proteins of viruses, fungi,
protozoa.
• Food, pollen, and dust can also contain
antigenic particles
• Enter the body by various methods
– Through breaks in the skin and mucous membranes
– Direct injection, as with a bite or needle
– Through organ transplants and skin grafts
Image: Antibody & antigens, Fvasconcellos From the Virtual Cell Biology Classroom on ScienceProfOnline.com
19. ___________
• Also called immunoglobulins (Ig)
• Proteinaceous molecules that bind antigens
• Considered part of the humoral immune
response since bodily fluids such as lymph
and blood were once called humors
• Can act as labels to identify
antigens for elimination from body.
• Other anitbodies …
- work as antitoxins
- attach to bacterial flagella
- cause agglutination (clumping together)
Image: Antibody & antigens, Fvasconcellos
A little bit of immunology to help you understand blood types.
Immunology Terms
From the Virtual Cell Biology Classroom on ScienceProfOnline.com
20. The interaction
of antibodies
and antigens is
how your body
tells the
difference
between self
and non-self.
Image: Antibody & antigens, Fvasconcellos;
Phagocytosis, Graham Colm
A little bit of immunology to help you understand blood types.
Immunology Terms
From the Virtual Cell Biology Classroom on ScienceProfOnline.com
21. Co-domiance : ____ _____ _____
- Has three alleles: A, B & O
- AB co-dominant, O recessive
- Genotype represented using
IA, IB & i
Phenotype Genotype
Type A IAIA or IAi
Type B IBIB or IBi
Type AB IAIB
Type O ii
Image: ABO blood type, InvictaHOG From the Virtual Cell Biology Classroom on ScienceProfOnline.com
22. ABO Blood Type
You make antibodies against the
antigens of other blood types. .
– Q: Which blood type can
accept anyone's blood.
– Q: Which blood type is known
as the “universal donor. Why?
Phenotype Genotype
Type A IAIA or IAi
Type B IBIB or IBi
Type AB IAIB
Type O ii
Image: ABO blood type, InvictaHOG From the Virtual Cell Biology Classroom on ScienceProfOnline.com
23. ABO Blood Type
If you are infused with
incompatable blood,
_________ occurs.
The antigens in your blood
bind to the antibodies of the
donor blood and cause the
blood to clump.
Image: Bedside blood grouping card,
AspersOn; ABO blood type, InvictaHOG From the Virtual Cell Biology Classroom on ScienceProfOnline.com
25. Mendelian Inheritance
Activity
Now it’s time to work on
the Mendelian
Inheritance worksheet.
You may work in groups,
helping each other
interpret traits.
Raise your hand if you
would like my help.
Completed worksheet is
due before you leave
class today.
Image: Simple Inheritance, complete
dominance, Magnus Manske
See the ScienceProfOnline Virtual Cell Biology
Classroom Mendilian Genetics & Heredity for a
printable Word .doc of this assignment.
From the Virtual Cell Biology Classroom on ScienceProfOnline.com
26. Are you feeling blinded by science?
Do yourself a favor. Use the…
Virtual Cell Biology
Classroom (VCBC) !
The VCBC is full of resources to help you succeed,
including:
• practice test questions
• review questions
• study guides and learning objectives
• PowerPoints on other topics
You can access the VCBC by going to the Science Prof Online website
www.ScienceProfOnline.com
Images: Blinded With Science album, Thomas Dolby; Endomembrane system, Mariana Ruiz, Wiki
